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Electric discharge coating is an alternative process for surface modification/alloying/coating requirements to improve mechanical and metallurgical properties of the materials. The high-pressure compacted electrode is made of the semi-sintered nickel and tungsten during the electric discharging process which influences the material migration towards substrate. In this proecess addtiton of pyrolysis carbon from dielectric togeather with the alloying elements and substrate material results in formation of metal matrix composite coating. It depended on the stabilization pressure of spark which increases the deposition rate of alloying materials and reduces the carbon, brittleness, cracks, voids, blowhole on the surface and made the layer to be desired metallurgical properties. Modified layer shows higher in hardness value of 1100 HV0.5 and reduction in specific wear to 0.082 × 10 −5 mm 3 /Nm compared with uncoated substrate material. Inclusion of the alloying material and reduction of the carbon percentage consequences in self-lubricant properties which alter the wear rate and coefficient of friction. Surfaces topography obtained during alloying, material migration and the mechanism have been characterized through scanning electron microscopy and energy-dispersive X-ray spectroscopy. The wear behaviour has been analysed by using pin-on-disc tribometer.

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Electrical discharge alloying was performed on AISI-D2 steel using Ni-Wp owder mixed dielectrici no rder to improve the hardness and to reduce the specific wear rate. The alloyed layer was characterized using optical microscopy,s canning electron microscopy, X-ray diffraction analysis and energy-dispersive spectroscopy. Wear tests were conducted based on L9 orthogonalarray in apin-ondisc tribometer and the alloying parameters were optimized using Taguchi's technique. Hard intermetallics based on Fe 7 C 3 ,C r 3 C 2 and Ni 2 W 4 Cw ere formed by electric discharge alloying, which primarilyc ontributed to the improvementi nh ardness up to 600 HV 0.5 .T he specific wear rate of the alloyed layer was subsequently reduced by around afactor of eightcompared to that of the base material. The pulse off-time was found to be predominant in obtaining higher hardness and lower specific wear rate among the alloyingp arameters, peak current, pulse on-time and off-time.